The present invention relates generally to optical interfaces for data communication and, more particularly, to a ferrule-less optical fiber apparatus for optical backplane connector systems.
There are many well-recognized benefits of using optical fiber to replace copper wiring for printed circuit boards (PCBs) in computer and networking equipment. Such potential benefits include increased bandwidth and data rate, overcoming bottlenecks in the processing architecture, immunity to electromagnetic interference and reductions in radiated noise from the system, reduced latency by elimination of optical/electrical (OLE) conversions, more dense packaging at lower cost per pin, and enablement of new processor interconnect technologies such as meshed rings. These and other factors directly contribute to the performance of the computer system (e.g., increased processing power in MIPS (million instructions per second) or FLOPS (floating-point operations per second), increased node count in parallel architectures, etc.).
However, in order to fully realize these benefits, an optical fiber interconnect should also continue to provide the same benefits of the existing electrical connection technologies. Heretofore, this issue has been one of the inhibitors to widespread use of optical fiber connection technology. As compared with copper interconnects, optical interconnects tend to require fairly high-precision, costly, and difficult to assemble components that are not particularly xe2x80x9cuser friendlyxe2x80x9d to field technicians lacking specific training in fiber optics.
For example, conventional duplex fiber optic connectors such as the SC (manufactured by IBM and Siecor) and ST (by ATandT) employ very precise ceramic ferrules and alignment sleeves to provide a means for bringing two optical fiber end faces into physical contact with one another. Actual physical contact is implemented in order to avoid excessively high optical losses, unwanted reflections, and other forms of noise. As such, a spring-loaded connector with some degree of float is used to facilitate the alignment of the fibers. Other types of multifiber ferrules have been proposed, such as the 12-fiber MT (manufactured by Fujikura, Siecor and AMP and others), which can be made of thermoplastic materials and employ precision stainless steel pins and a guide hole to achieve alignment of the fiber array. Unfortunately, both of these connector designs are inherently expensive, because the precision required for either ceramic ferrules or MT guide pins is on the order of a few microns to submicron dimensions.
Furthermore, despite the fact that ferrules are produced by the millions, the basic high-volume price thereof has not changed significantly over the years. The ceramic parts alone in a duplex connector can cost around $6, while MT ferrule components themselves can run into the $10-20 range. The metal springs used to maintain physical contact between fibers and related elements in the connector further increase the cost. In addition, the process of threading an optical fiber (e.g., having an outer diameter of about 125xc2x11 microns) into a precision hole (e.g., having a maximum diameter less than 127 microns) has traditionally been a very difficult process to automate using factory-terminated, ferrule-based connectors. While field termination is possible for duplex connectors, it is not an option for multi-fiber connectors. Moreover, even where epoxy-free field terminations are used, it can still take 5-10 minutes (or even longer) to field terminate a duplex fiber connector (as compared to 1-2 minutes for a category-5 UTP copper connector), thereby further increasing the overall installation costs.
Accordingly, it would be desirable to be able to implement a fiber optic connector for multi-fiber, parallel backplane interfaces that provides the benefits of both optical fiber technology and the copper interconnect interfaces currently in use.
The foregoing discussed drawbacks and deficiencies of the prior art are overcome or alleviated by a ferrule-less optical backplane connector assembly. In an exemplary embodiment, the assembly includes a substrate having at least a pair of optical guide receiving structures formed therein, the pair of optical guide receiving structures further being formed at substantially a right angle with respect to one another so as to guide a corresponding first and second optical guide into optical alignment with one another.
In another aspect, a ferrule-less optical backplane connector apparatus includes a laminate assembly having a plurality of V-shaped grooves formed within individual layers thereof. The V-shaped grooves are formed at substantially right angle pairs with respect to one another, and are configured for guiding and optically coupling a corresponding pair of optical guides inserted within orthogonal sides of the laminate assembly.
In yet another aspect, a method for forming a ferrule-less optical backplane connector assembly includes forming orthogonally intersecting pairs of V-shaped grooves within a plurality of workpieces. An index-matching fluid is inserted within each pair of the V-shaped grooves. Then, the plurality of workpieces are stacked and bonded to form a generally cube-shaped, laminate assembly. The pairs of V-shaped grooves in individual layers of the laminate assembly are vertically aligned so as to receive arrays of optical guides within orthogonal sides of the assembly.